Red Bull’s Max Verstappen has been stripped of pole position for impeding Mercedes driver George Russell in qualifying at the Qatar Grand Prix.
The judgement reverses the places on the front row, with Russell promoted to pole and Verstappen demoted to second place.
Verstappen, who had beaten Russell to pole by 0.055 seconds, was penalised for driving unnecessarily slowly and impeding his rival.
The two cars tangled at Turn 12, forcing Russell on to the gravel.
Verstappen was penalised for driving unnecessarily slowly and found to have been "well outside" the target time required of drivers when not on a flying lap.
The stewards said there were mitigating circumstances as neither driver was on a flying lap, but ruled that Verstappen had broken the rules.
They sided with Russell's argument that Verstappen should not have been on the racing line if he was going slowly.
The ruling said: "The stewards regard this case as a complicated one in that clearly [Verstappen] did not comply with the race director's event notes and clearly was driving, in our determination, unnecessarily slowly considering the circumstances.
"It was obvious [Verstappen] was attempting to cool his tyres. He also could see [Russell] approaching as he looked in his mirror multiple times while on the small straight between Turns 11 and 12.
"Unusually, this incident occurred when neither car was on a push lap.
"Had [Russell] been on a push lap, the penalty would have most likely been the usual three-grid position penalty.
"However, in mitigation of penalty, it was obvious that [Russell] had clear visibility of [Verstappen]."
A one-place penalty is highly unusual. Three-place penalties are normally handed out when a driver has impeded a rival on a flying - or 'push' - lap.
But that was not the case this time.
BBC Sport has been told that the stewards felt they needed to find a middle ground between a standard three-place penalty and a reprimand, which would be standard for the offence Verstappen committed if he had been alone on track.
The tendency is to go for odd-numbered penalties because they put the driver on the opposite side of the grid from where he originally qualified.
In this case, Verstappen's move to second puts him on the dirtier side of the grid, where there is less grip, and from where many cars made slower starts in the sprint race on Saturday.
An added factor in the decision was that the incident was not felt by the stewards to be dangerous, and there was a feeling Russell exaggerated the incident.
A one-place penalty was given to Sergio Perez, then driving for Racing Point, at the 2020 Tuscan Grand Prix, when the Mexican collided with Kimi Raikkonen's Alfa Romeo, which ended up in the gravel.
Russell had been on provisional pole after the first runs in the final session but was pipped by 0.055 seconds by Verstappen’s final lap.
Russell felt the Verstappen incident had prevented his tyres being in the right operating window for his final lap, on which he did not improve.
The Mercedes driver said: "I expected to improve on the second lap and had a scrappy out lap, nearly had the collision with Max and went into the gravel two corners before I started it.
"The time was in the car but as soon as I went into Turn One the car and tyres just didn’t feel right and I was in the gravel two corners before I started my lap.
"It was a shame it ended that way."
McLaren drivers Lando Norris and Oscar Piastri took third and fourth, after the Australian led a one-two in the sprint race earlier in the day.
Ferrari’s Charles Leclerc took fifth from Mercedes’ Lewis Hamilton, Ferrari’s Carlos Sainz and Aston Martin’s Fernando Alonso.
Despite losing pole, Verstappen’s performance was a remarkable turnaround after the Red Bull had finished an uncompetitive eighth in the sprint.
The world champion had complained of no grip or balance in the sprint but the team found a better set-up for the main qualifying session.
Verstappen said: "Crazy. Honestly, I also didn't expect that. Well done to the team to give me a car that feels a bit more connected and once the car is more together you can push a lot harder.
"We did change a bit on the car but I never thought it would make such a swing in performance, it felt a lot more stable over one lap and that is exactly what we need."
Russell said: "I was really surprised by [Red Bull’s] turnaround. I think we've got a good race on our hands."
Norris, who dominated the sprint race before handing victory to Piastri on the run to the line, was 0.252secs off pole.
"Not the position we were hoping for after yesterday and today but the maximum we could do," Norris said. "The lap was pretty good. It was pretty happy with it but just not quick enough compared to the others.
"Not a lot in it between all of us, which gives us hope we can all go forwards. We showed good race pace today I did gave the benefit of being out front and having clean air but I think we still have a good chance.
"I don't think we are as quick as the Mercedes and Red Bull showed how much they improved since yesterday."
McLaren can clinch the constructors' championship in the grand prix, but only if they finish one-two and take the fastest lap.
Hamilton was 0.491secs off pole but managed to split the Ferraris, while eighth was an encouraging performance for Alonso after a difficult season for Aston Martin. The veteran two-time champion was just 0.21secs off Sainz's Ferrari, and 0.174secs quicker than Perez's Red Bull.
For the Mexican, it was a better result after a dire performance in the sprint, which he started from the pit lane and was caught napping at the lights when he did not go straight away and was passed by Williams' Franco Colapinto.
But he was still 0.905secs off Verstappen and his future in the team remains in doubt.